Just here for the obligatory Why would you downgrade your computer?
Microsoft has announced that they are making a start-to-desktop and start menu mod. That is on top of the many $5 option out there.
I couldn't imagine downgrading from Win 8 after I've used it. Not only is it fast, the security is top-notch, and the auto-back-ups it generates (via option) are very convenient.
Windows 7 is an upgrade. And I'd like to see a link to an article about this "mod" you say Microsoft will be including. As far as I know, Microsoft could care less that its user base want a start menu.